Wiring for 12 volt DC circuits is of the multi stranded type, or commonly just called “stranded”. Stranded wire, instead of being one solid piece, like you might find in your house, is divided into many small strands. These strands are encapsulated in an insulating material. Stranded wire is usually used in areas that move or receive more vibration like boats, RV’s, airplanes, and the like. Single strand wire can break or weaken under the same conditions. Stranded wire is somewhat easier to work with.

Big Easy Wiring Mistake - Mixing Positive and Negative Wire

Except for DC devices and components that just plug into a receptacle like the power plug in your car, 12 volt systems have positive connectors and negative connectors. You can’t mix them up! Your battery will have a positive post (or two) and a negative post, as will your inverter, solar panels, charge controller and most every other do-dad you add to it.

For example, the negative wire off the inverter connects to the negative post on the battery, the negative wire off the solar panel connects to the negative connection on the charge controller which connects to the negative post on the battery. Same for the positive wires except, of course, they’re connected to the positive connectors and posts. Solar panels, charge controllers, inverters, etc. come with wiring instructions, well, not always. Follow them carefully if you’ve got them.

Some Common Solar Wiring Connectors for Small Systems

Ring terminals

Wires don’t come with ends; ends to connect them to something else. One common “end” is the ring terminal or insulated ring terminal. The ring terminal is a small metal ring that’s crimped onto the wire you tape with electrical tape or other protective insulator. This ring terminal could be used to fit onto the secondary posts of your battery. It may be used to connect two wires together that you might want to separate later. (You could use a nut and bolt.) These also come in sizes, not only physically, but according to gauge. Everything must fit and be strong enough to handle the electricity running through it including the ring terminal.

Fork terminals

A fork terminal is a terminal similar to the above but in a U shape.

Butt splices

Sometimes a wire is just too short. You can connect one wire to another using a butt splice. It’s just a small connector that allows you to crimp two wires together. Gauge is an issue here as well.